The finest collection of 20th-century western art outside Europe and America has been gathering dust in storage. Why? Because it's owned by the Islamic Republic of Iran. But now, Christopher de Bellaigue reports, these spectacular works are finally being displayed in Tehran An Iranian woman stands in front of a huge Picasso, Painter and his Model, on show at Tehran's Museum of Contemporary Art. Standing in his studio, illuminated by subdued pools of coloured light, the artist is depicted as an extension of the inanimate objects around him. He has been reduced to a series of mostly straight lines; his...